This invention relates to a bass-control arrangement with an electronically controllable transfer characteristic and with the input signal applied to an amplifier having controllable negative feedback.
Such a circuit arrangement is known from DE-PS No. 24 04 331 and DE-PS No. 22 62 089. The negative feedback of the amplifier, and consequently the transfer characteristic of the circuit arrangement, is varied in that the current distribution between two differential amplifiers is varied in an opposite sense by means of a direct voltage. The inputs of the two differential amplifiers are coupled to each other either via a frequency-independent network so that a volume control device is obtained (DE-PS No. 24 04 331), or via a frequency-dependent network (DE-PS No. 22 62 089), so that a tone control device (treble or bass control) is obtained.
A disadvantage of circuit arrangements which are based on the variation of the current distribution between two differential amplifiers is that they exhibit a comparatively large amount of noise. Moreover, if such a circuit arrangement is constructed as an integrated circuit at least three external connection terminals must be provided for connection of the negative feedback network and the external connections to such an integrated circuit are comparatively intricate, at least when said circuit is used as a tone control device.